JPH11153137A - Static pressure direct-acting gas bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a static pressure direct-acting gas bearing realizing miniaturization, light weight, and low cost by reducing the number of parts and simplifying the structure. SOLUTION: A shaft body 11 is made of perforated material and a ventilation hole 13 drilled on the shaft body 11 is connected to a compressed air duct and ventilates to the perforated material. Hence, compressed air supplied to the ventilation hole 13 is diffused and spread being squeezed in the shaft body 11, and gushed out into the bearing space S between the shaft body 11 and a bearings body 12 to form a fluid film in the bearing space S. Either one of the bearing body 12 or the shaft body 11 can make direct-acting without contact.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrostatic direct acting gas bearing, and more particularly, to a static pressure linear bearing used for a semiconductor manufacturing apparatus such as a bonding apparatus and a mounting, which has been reduced in size, weight, and cost. The present invention relates to a pressure direct acting gas bearing.

[0002]

2. Description of the Related Art As a conventional hydrostatic direct-acting gas bearing, for example, as shown in FIGS. 5 and 6, a shaft 3 (for example, a guide rail) is mounted on a base 1 via a support 2, and a bolt 4 is provided. Around this shaft body 3, a square frame-shaped bearing body 5 (for example, an air slide) is slidably provided so as to be moved within a range indicated by imaginary lines A and B. ing.

As shown in FIG. 6, the bearing body 5 includes an upper frame member 6, a lower frame member 7, and a pair of horizontal members connecting the upper frame member 6 and the lower frame member 7 to form a square frame. Frame members 8, 9
The bearing surfaces of the frame members 6, 7, 8, 9 are opposed to the bearing surface of the shaft body 3 with a predetermined bearing gap S therebetween. Further, each of the frame members 6, 7, 8, 9 has a porous body 6a,
7a, 8a, 9a (pads) are provided so as to be buried therein. Each of the frame members 6, 7, 8, 9 is provided for supplying compressed air to these porous bodies 6a, 7a, 8a, 9a. Vent holes 6b, 7b, 8b, 9b are formed. These ventilation holes 6b, 7b, 8b, 9b communicate with each other,
It is connected to the compressed air pipe 10 shown in FIG.

Therefore, compressed air is supplied from the compressed air pipe 10 to the porous body 6 through the ventilation holes 6b, 7b, 8b, 9b.
When the compressed air is supplied and squeezed to the a, 7a, 8a, and 9a, the compressed air is jetted into the bearing gap S to form a fluid film, thereby supporting the bearing body 5 in a non-contact manner with the shaft body 3. And can be slid.

[0005]

However, in the hydrostatic direct-acting gas bearing shown in FIGS. 5 and 6, each of the frame members 6 to 9 constituting the bearing body 5 is provided with a separate porous member. Since it is necessary to bury the bodies 6a to 9a, each frame member 6 to 9a
9, the thickness of the movable body 5 becomes large, and it is difficult to reduce the size and weight of the movable body 5.

In addition, since it is necessary to embed the porous bodies 6a to 9a in the frame members 6 to 9 to perform the compressed air throttle action, the number of parts must be increased. There is.

Further, ventilation holes 6b to 9b communicating with the porous bodies 6a to 9a must be formed in each of the frame members 6 to 9, and a connection port between these ventilation holes 6b to 9b and the compressed air pipe 10 ( (Not shown) and the like are necessary, so that it may be difficult to reduce the size, weight, and cost of the bearing body 5.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has a static pressure that is reduced in size, weight, and cost by reducing the number of parts and simplifying the structure. It is an object to provide a linear motion gas bearing.

[0009]

To achieve the above object, a hydrostatic direct acting gas bearing according to the present invention is provided with a bearing body around a shaft through a bearing gap, and supplies compressed air to the bearing gap. In a hydrostatic direct acting gas bearing in which the bearing body and the shaft body are not in contact,
Either the shaft body or the bearing body can move linearly with respect to the other, and the shaft body is made of a porous material whose axial position is equal to that of the bearing body when the hydrostatic direct acting gas bearing is operated in the axial direction. A vent formed from a material and provided in the shaft is connected to a compressed air pipe and supplies air to the porous material.

As described above, according to the present invention, the shaft body is formed of a porous material so that the axial position of the shaft body is equal to that of the bearing body during operation of the bearing. When compressed air is supplied to the porous material from the compressed air pipe through the vent hole to supply air to the porous material, the compressed air spreads while being squeezed by the porous material while being diffused. It squirts into the bearing gap between the bearing and the bearing body to form a fluid film in the bearing gap, whereby one of the bearing body and the shaft body is supported without contact with the other and slides. Can be moved.

Therefore, in the present invention, on the bearing body side,
As before, compressed air vents, connections to vents,
Since there is no need to provide a porous body, the thickness of the bearing body can be reduced, the number of parts can be reduced, the structure can be simplified, and the size and weight of the hydrostatic gas bearing can be reduced. And cost can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hydrostatic direct acting gas bearing according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a hydrostatic direct acting gas bearing according to a first embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of the hydrostatic direct acting gas bearing shown in FIG. .

In the first embodiment, a square frame-shaped movable body bearing member 12 (for example, an air slide) forms a bearing gap S around a prismatic fixed shaft member 11 (guide rail). It is slidably provided through the actuator and is moved in a range indicated by virtual lines A and B.

The shaft body 11 is formed of a porous material having an appropriate air permeability as an air bearing, for example, a graphite material, a ceramic porous material, or a sintered copper material. However, the material of the shaft body 11 is not limited to the illustrated one as long as it is a porous material as described above. A ventilation hole 13 is formed in the shaft body 11 so as to penetrate in the axial direction. A connection port 14 for connecting a compressed air pipe (not shown) is formed at one end of the ventilation hole 13.
At the other end, an airtight material 15 is embedded. This allows
The compressed air supplied from the compressed air piping is diffused and spread while being squeezed by the porous material of the shaft body 11 from the connection port 14 through the ventilation hole 13, and is blown out from the outer surface of the shaft body 11. .

As shown in FIG. 1, the bearing body 12 includes an upper frame member 16, a lower frame member 17, and a pair of horizontal frames connecting the upper frame member 16 and the lower frame member 17 to form a square frame. Members 18 and 19, and these frame members 16, 17 and
The four bearing surfaces 18 and 19 are opposed to the four bearing surfaces of the shaft body 11 with a predetermined bearing gap S therebetween. The upper frame member 16 and the lower frame member 17 are fastened by bolts 20 penetrating the horizontal frame members 18 and 19, whereby the surface accuracy of a predetermined bearing gap S is ensured, and a square frame-shaped bearing body is provided. 12 are assembled. It is not necessary to provide a compressed air vent, a connection port to the vent, and a porous body on the bearing body 12 side as in the related art. Since the shaft body 11 is formed of a porous material, a portion of the shaft body 11 which is equal in axial position to the bearing body 12 when the hydrostatic direct acting gas bearing is operated in the axial direction is formed of porous material.

In the first embodiment, as described above, when compressed air is supplied from a compressed air pipe (not shown) through the connection port 14 and the ventilation hole 13, the compressed air is removed from the shaft body. The porous body 11 spreads while being squeezed while being squeezed, and squirts into a bearing gap S between the shaft body 11 and the bearing body 12 to form a fluid film in the bearing gap S. Can be moved linearly while supporting the shaft member 11 in a non-contact manner.

Therefore, in the first embodiment, there is no need to provide a compressed air vent, a connection port to the vent, and a porous body on the bearing body 12 side unlike the conventional case. The plate thickness of the body 12 can be reduced, the number of parts can be reduced, and the structure can be simplified. As a result, the size, weight, and cost of the hydrostatic direct acting gas bearing can be reduced.

Also, there is no need to provide a compressed air vent, a connection port to the vent, and a porous body on the bearing body 12 side, and the compressed air pipe is connected to the shaft body 11 side. In a case where the bearing body 12 is positioned at a predetermined position and stopped, even if the compressed air piping is deformed, the bearing body 12 is not affected by such a situation, and the bearing body 12 is not moved. It can be positioned accurately.

FIG. 3 is a cross-sectional view of a hydrostatic direct acting gas bearing according to a second embodiment of the present invention, and FIG.
FIG. 2 is a longitudinal sectional view of the hydrostatic direct acting gas bearing shown in FIG.

In the second embodiment, a cylindrical movable body bearing 11 is mounted on a cylindrical fixed body shaft 11 (guide rail).
2 (for example, an air slide) is provided so as to be slidable, and is moved within a range indicated by virtual lines A and B.

The fixed body 11 is, as in the first embodiment,
It is formed of a porous material having an appropriate air permeability as a hydrostatic direct acting gas bearing, for example, a graphite material, a ceramic porous material, a sintered copper material, or the like. Connection port 1 for connecting (not shown)
4 is formed, and the other end of the ventilation hole 13 is provided with an airtight material 15.
Is plugged.

As shown in FIG. 2, the bearing body 12 is formed of a cylindrical member. The inner peripheral bearing surface of the cylindrical bearing body 12 is different from the outer peripheral bearing surface of the shaft body 11. , A predetermined bearing gap S is interposed therebetween, and the surface accuracy of the predetermined bearing gap S is ensured.

Also in the second embodiment, since the structure is as described above, when compressed air is supplied from a compressed air pipe (not shown) through the connection port 14 and the ventilation hole 13, the compressed air 11, while being squeezed by the porous material, diffuses and spreads, and squirts into a bearing gap S between the cylindrical shaft body 11 and the cylindrical bearing body 12 to form a fluid film in the bearing gap S; Thereby, the bearing body 12 can be supported and slid on the shaft body 11 in a non-contact manner.

Therefore, in the second embodiment, since the hydrostatic direct acting gas bearing is constituted only by the two members of the cylindrical shaft 11 and the cylindrical bearing 12, the number of parts can be reduced. At the same time, the structure can be simplified, and the size, weight and cost of the hydrostatic direct acting gas bearing can be reduced.

The shaft body 11 may be able to move directly with respect to the bearing body 12, and the present invention is not limited to the above-described embodiment, but can be variously modified.

[0027]

As described above, according to the present invention,
The shaft body is made of porous material to make the axial position equal to that of the bearing body when the hydrostatic direct acting gas bearing is operated in the axial direction. The ventilation holes provided in this shaft body are connected to the compressed air piping and In order to supply air to the material, compressed air is throttled in the shaft and blows out into the bearing gap, so that one of the bearing and the shaft can move directly without contact with the other. Therefore, the number of parts can be reduced, and the structure can be simplified.
As a result, it is possible to reduce the size, weight, and cost of the hydrostatic direct acting gas bearing.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a hydrostatic direct acting gas bearing according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the hydrostatic direct acting gas bearing shown in FIG.

FIG. 3 is a cross-sectional view of a hydrostatic direct acting gas bearing according to a second embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of the hydrostatic direct acting gas bearing shown in FIG. 3;

FIG. 5 is a side view of a conventional hydrostatic gas bearing.

6 is a cross-sectional view of the conventional hydrostatic direct acting gas bearing shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Shaft body 12 Bearing body 13 Vent hole 14 Connection port 15 Airtight material 16 Upper frame member 17 Lower frame member 18, 19 Horizontal frame member 20 Bolt

Claims (1)

[Claims] 1. A hydrostatic direct acting gas bearing in which a bearing is provided around a shaft via a bearing gap and compressed air is supplied to the bearing gap so that the bearing and the shaft are not in contact with each other. One of the bearing and the bearing body can move directly with respect to the other, and the shaft body is made of a porous material to make the position of the bearing body and the axial position equal during the axial operation of the hydrostatic direct acting gas bearing. A hydrostatic direct acting gas bearing characterized in that a shaft is connected to a compressed air pipe and a vent is provided for supplying air to a porous material.